[runtimes] Unify exception and RTTI configuration for the runtimes

libcxx/CMakeLists.txt

@@ -47,10 +47,6 @@ include(HandleCompilerRT)
 # Basic options ---------------------------------------------------------------
 option(LIBCXX_ENABLE_SHARED "Build libc++ as a shared library." ON)
 option(LIBCXX_ENABLE_STATIC "Build libc++ as a static library." ON)
-option(LIBCXX_ENABLE_EXCEPTIONS "Enable exceptions in the built library." ON)
-option(LIBCXX_ENABLE_RTTI
-  "Use runtime type information.
-  This option may only be set to OFF when LIBCXX_ENABLE_EXCEPTIONS=OFF." ON)
 option(LIBCXX_ENABLE_FILESYSTEM
   "Whether to include support for parts of the library that rely on a filesystem being
    available on the platform. This includes things like most parts of <filesystem> and
@@ -164,8 +160,8 @@ if (WIN32 OR MINGW OR ANDROID OR "${CMAKE_SYSTEM_NAME}" MATCHES "AIX"
     OR NOT LIBCXX_ENABLE_THREADS
     OR NOT LIBCXX_ENABLE_FILESYSTEM
     OR NOT LIBCXX_ENABLE_RANDOM_DEVICE
-    OR NOT LIBCXX_ENABLE_EXCEPTIONS
-    OR NOT LIBCXX_ENABLE_RTTI)
+    OR NOT RUNTIMES_ENABLE_EXCEPTIONS
+    OR NOT RUNTIMES_ENABLE_RTTI)
   set(_include_benchmarks OFF)
 else()
   set(_include_benchmarks ON)
@@ -358,12 +354,6 @@ if (LIBCXX_HAS_PTHREAD_API)
   endif()
 endif()
 
-if (NOT LIBCXX_ENABLE_RTTI AND LIBCXX_ENABLE_EXCEPTIONS)
-  message(FATAL_ERROR "Libc++ cannot be built with exceptions enabled but RTTI"
-                      " disabled, since that configuration is broken. See"
-                      " https://llvm.org/PR66117 for details.")
-endif()
-
 if (LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
     if (APPLE)
       message(FATAL_ERROR "LIBCXX_ENABLE_ABI_LINKER_SCRIPT cannot be used on APPLE targets")
@@ -540,29 +530,6 @@ function(cxx_add_basic_build_flags target)
   target_compile_options(${target} PUBLIC "${LIBCXX_ADDITIONAL_COMPILE_FLAGS}")
 endfunction()
 
-# Exception flags =============================================================
-function(cxx_add_exception_flags target)
-  if (LIBCXX_ENABLE_EXCEPTIONS)
-    # Catches C++ exceptions only and tells the compiler to assume that extern C
-    # functions never throw a C++ exception.
-    target_add_compile_flags_if_supported(${target} PUBLIC -EHsc)
-  else()
-    target_add_compile_flags_if_supported(${target} PUBLIC -EHs- -EHa-)
-    target_add_compile_flags_if_supported(${target} PUBLIC -fno-exceptions)
-  endif()
-endfunction()
-
-# RTTI flags ==================================================================
-function(cxx_add_rtti_flags target)
-  if (NOT LIBCXX_ENABLE_RTTI)
-    if (MSVC)
-      target_add_compile_flags_if_supported(${target} PUBLIC -GR-)
-    else()
-      target_add_compile_flags_if_supported(${target} PUBLIC -fno-rtti)
-    endif()
-  endif()
-endfunction()
-
 # Modules flags ===============================================================
 # FIXME The libc++ sources are fundamentally non-modular. They need special
 # versions of the headers in order to provide C++03 and legacy ABI definitions.
@@ -817,11 +784,10 @@ function(cxx_add_common_build_flags target)
   cxx_add_basic_build_flags(${target})
   cxx_add_warning_flags(${target} ${LIBCXX_ENABLE_WERROR} ${LIBCXX_ENABLE_PEDANTIC})
   cxx_add_windows_flags(${target})
-  cxx_add_exception_flags(${target})
-  cxx_add_rtti_flags(${target})
   cxx_add_module_flags(${target})
   cxx_link_system_libraries(${target})
   target_link_libraries(${target} PRIVATE cxx-sanitizer-flags)
+  target_link_libraries(${target} PRIVATE runtimes-language-flags)
 endfunction()
 
 #===============================================================================

libcxx/cmake/caches/AMDGPU.cmake

@@ -1,12 +1,14 @@
+# Configuration options for all the runtimes
+set(RUNTIMES_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
+set(RUNTIMES_ENABLE_RTTI OFF CACHE BOOL "")
+
 # Configuration options for libcxx.
 set(LIBCXX_CXX_ABI libcxxabi CACHE STRING "")
-set(LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
 set(LIBCXX_ENABLE_FILESYSTEM OFF CACHE BOOL "")
 set(LIBCXX_ENABLE_LOCALIZATION ON CACHE BOOL "")
 set(LIBCXX_ENABLE_MONOTONIC_CLOCK ON CACHE BOOL "")
 set(LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS ON CACHE BOOL "")
 set(LIBCXX_ENABLE_RANDOM_DEVICE OFF CACHE BOOL "")
-set(LIBCXX_ENABLE_RTTI OFF CACHE BOOL "")
 set(LIBCXX_ENABLE_SHARED OFF CACHE BOOL "")
 set(LIBCXX_ENABLE_STATIC_ABI_LIBRARY ON CACHE BOOL "")
 set(LIBCXX_ENABLE_STATIC ON CACHE BOOL "")
@@ -21,7 +23,6 @@ set(RUNTIMES_USE_LIBC "llvm-libc" CACHE STRING "")
 
 # Configuration options for libcxxabi.
 set(LIBCXXABI_BAREMETAL ON CACHE BOOL "")
-set(LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
 set(LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
 set(LIBCXXABI_ENABLE_SHARED OFF CACHE BOOL "")
 set(LIBCXXABI_ENABLE_THREADS OFF CACHE BOOL "")

libcxx/cmake/caches/Armv7M-picolibc.cmake

@@ -6,6 +6,8 @@ set(CMAKE_C_FLAGS "-mfloat-abi=soft" CACHE STRING "")
 set(CMAKE_SYSTEM_NAME Generic CACHE STRING "")
 set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY CACHE STRING "")
 set(LLVM_USE_LINKER "lld" CACHE STRING "")
+set(RUNTIMES_ENABLE_EXCEPTIONS ON CACHE BOOL "")
+set(RUNTIMES_ENABLE_RTTI ON CACHE BOOL "")
 set(COMPILER_RT_BAREMETAL_BUILD ON CACHE BOOL "")
 set(COMPILER_RT_BUILD_LIBFUZZER OFF CACHE BOOL "")
 set(COMPILER_RT_BUILD_PROFILE OFF CACHE BOOL "")
@@ -14,17 +16,14 @@ set(COMPILER_RT_BUILD_XRAY OFF CACHE BOOL "")
 set(COMPILER_RT_DEFAULT_TARGET_ONLY ON CACHE BOOL "")
 set(LIBCXXABI_BAREMETAL ON CACHE BOOL "")
 set(LIBCXXABI_ENABLE_ASSERTIONS OFF CACHE BOOL "")
-set(LIBCXXABI_ENABLE_EXCEPTIONS ON CACHE BOOL "")
 set(LIBCXXABI_ENABLE_SHARED OFF CACHE BOOL "")
 set(LIBCXXABI_ENABLE_STATIC ON CACHE BOOL "")
 set(LIBCXXABI_ENABLE_STATIC_UNWINDER ON CACHE BOOL "")
 set(LIBCXXABI_ENABLE_THREADS OFF CACHE BOOL "")
 set(LIBCXXABI_USE_COMPILER_RT ON CACHE BOOL "")
-set(LIBCXX_ENABLE_EXCEPTIONS ON CACHE BOOL "")
 set(LIBCXX_ENABLE_FILESYSTEM OFF CACHE STRING "")
 set(LIBCXX_ENABLE_MONOTONIC_CLOCK OFF CACHE BOOL "")
 set(LIBCXX_ENABLE_RANDOM_DEVICE OFF CACHE BOOL "")
-set(LIBCXX_ENABLE_RTTI ON CACHE BOOL "")
 set(LIBCXX_ENABLE_SHARED OFF CACHE BOOL "")
 set(LIBCXX_ENABLE_STATIC ON CACHE BOOL "")
 set(LIBCXX_ENABLE_THREADS OFF CACHE BOOL "")

libcxx/cmake/caches/Armv7Thumb-no-exceptions.cmake

@@ -1,7 +1,6 @@
 set(CMAKE_CXX_COMPILER_TARGET "armv7l-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-mthumb" CACHE STRING "")
 set(CMAKE_C_FLAGS "-mthumb" CACHE STRING "")
-set(LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
-set(LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
+set(RUNTIMES_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
 set(LIBCXX_TEST_PARAMS "enable_modules=clang" CACHE STRING "")
 set(LIBCXXABI_TEST_PARAMS "${LIBCXX_TEST_PARAMS}" CACHE STRING "")

libcxx/cmake/caches/Armv8Thumb-no-exceptions.cmake

@@ -1,7 +1,6 @@
 set(CMAKE_CXX_COMPILER_TARGET "armv8l-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-mthumb" CACHE STRING "")
 set(CMAKE_C_FLAGS "-mthumb" CACHE STRING "")
-set(LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
-set(LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
+set(RUNTIMES_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
 set(LIBCXX_TEST_PARAMS "enable_modules=clang" CACHE STRING "")
 set(LIBCXXABI_TEST_PARAMS "${LIBCXX_TEST_PARAMS}" CACHE STRING "")

libcxx/cmake/caches/Generic-no-exceptions.cmake

@@ -1,5 +1,4 @@
-set(LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
-set(LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
+set(RUNTIMES_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
 
 # Speed up the CI
 set(LIBCXX_TEST_PARAMS "enable_modules=clang" CACHE STRING "")

libcxx/cmake/caches/Generic-no-rtti.cmake

@@ -1,7 +1,5 @@
-set(LIBCXX_ENABLE_RTTI OFF CACHE BOOL "")
-set(LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
-set(LIBCXXABI_ENABLE_RTTI OFF CACHE BOOL "")
-set(LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
+set(RUNTIMES_ENABLE_RTTI OFF CACHE BOOL "")
+set(RUNTIMES_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
 
 # Speed up the CI
 set(LIBCXX_TEST_PARAMS "enable_modules=clang" CACHE STRING "")

libcxx/cmake/caches/NVPTX.cmake

@@ -1,12 +1,14 @@
+# Configuration options for the runtimes.
+set(RUNTIMES_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
+set(RUNTIMES_ENABLE_RTTI OFF CACHE BOOL "")
+
 # Configuration options for libcxx.
 set(LIBCXX_CXX_ABI libcxxabi CACHE STRING "")
-set(LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
 set(LIBCXX_ENABLE_FILESYSTEM OFF CACHE BOOL "")
 set(LIBCXX_ENABLE_LOCALIZATION ON CACHE BOOL "")
 set(LIBCXX_ENABLE_MONOTONIC_CLOCK ON CACHE BOOL "")
 set(LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS ON CACHE BOOL "")
 set(LIBCXX_ENABLE_RANDOM_DEVICE OFF CACHE BOOL "")
-set(LIBCXX_ENABLE_RTTI OFF CACHE BOOL "")
 set(LIBCXX_ENABLE_SHARED OFF CACHE BOOL "")
 set(LIBCXX_ENABLE_STATIC_ABI_LIBRARY ON CACHE BOOL "")
 set(LIBCXX_ENABLE_STATIC ON CACHE BOOL "")
@@ -21,7 +23,6 @@ set(RUNTIMES_USE_LIBC "llvm-libc" CACHE STRING "")
 
 # Configuration options for libcxxabi.
 set(LIBCXXABI_BAREMETAL ON CACHE BOOL "")
-set(LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
 set(LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
 set(LIBCXXABI_ENABLE_SHARED OFF CACHE BOOL "")
 set(LIBCXXABI_ENABLE_THREADS OFF CACHE BOOL "")

libcxx/docs/Modules.rst

@@ -48,15 +48,10 @@ What works
    * ``LIBCXX_ENABLE_FILESYSTEM``
    * ``LIBCXX_ENABLE_RANDOM_DEVICE``
    * ``LIBCXX_ENABLE_UNICODE``
-   * ``LIBCXX_ENABLE_EXCEPTIONS`` [#note-no-windows]_
+   * ``RUNTIMES_ENABLE_EXCEPTIONS``
 
  * A C++20 based extension
 
-.. note::
-
-   .. [#note-no-windows] This configuration will probably not work on Windows
-                         due to hard-coded compilation flags.
-
 Some of the current limitations
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

libcxx/docs/VendorDocumentation.rst

@@ -227,18 +227,7 @@ General purpose options
 
   Additional libraries libc++ is linked to which can be provided in cache.
 
-.. option:: LIBCXX_ENABLE_EXCEPTIONS:BOOL
-
-  **Default**: ``ON``
-
-  Build libc++ with exception support.
-
-.. option:: LIBCXX_ENABLE_RTTI:BOOL
-
-  **Default**: ``ON``
-
-  Build libc++ with run time type information.
-  This option may only be set to OFF when LIBCXX_ENABLE_EXCEPTIONS=OFF.
+.. TODO: Where should we document the runtimes build options?
 
 .. option:: LIBCXX_INCLUDE_TESTS:BOOL
 

libcxx/lib/abi/CMakeLists.txt

@@ -53,7 +53,7 @@ cxx_abi_list_identifier(abi_list_identifier
   "${LIBCXX_CXX_ABI}"
   "${LIBCXX_ABI_VERSION}"
   "${LIBCXX_ABI_UNSTABLE}"
-  "${LIBCXX_ENABLE_EXCEPTIONS}"
+  "${RUNTIMES_ENABLE_EXCEPTIONS}"
   "${LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS}"
 )
 

libcxx/modules/CMakeLists.txt.in

@@ -43,10 +43,6 @@ target_sources(std
 
 target_include_directories(std SYSTEM PUBLIC @LIBCXX_CONFIGURED_INCLUDE_DIRS@)
 
-if (NOT @LIBCXX_ENABLE_EXCEPTIONS@)
-  target_compile_options(std PUBLIC -fno-exceptions)
-endif()
-
 target_compile_options(std
   PUBLIC
     -nostdinc++
@@ -58,7 +54,7 @@ target_compile_options(std
     -Wno-reserved-user-defined-literal
 )
 target_link_options(std PUBLIC -nostdlib++ -Wl,-rpath,@LIBCXX_LIBRARY_DIR@ -L@LIBCXX_LIBRARY_DIR@)
-target_link_libraries(std c++)
+target_link_libraries(std c++ runtimes-language-flags)
 set_target_properties(std
   PROPERTIES
     OUTPUT_NAME   "c++std"
@@ -74,10 +70,6 @@ target_sources(std.compat
 
 target_include_directories(std.compat SYSTEM PUBLIC @LIBCXX_CONFIGURED_INCLUDE_DIRS@)
 
-if (NOT @LIBCXX_ENABLE_EXCEPTIONS@)
-  target_compile_options(std.compat PUBLIC -fno-exceptions)
-endif()
-
 target_compile_options(std.compat
   PUBLIC
     -nostdinc++

libcxx/test/CMakeLists.txt

@@ -70,11 +70,11 @@ else()
   set(_libcxx_benchmark_mode "no")
 endif()
 
-if (NOT LIBCXX_ENABLE_EXCEPTIONS)
+if (NOT RUNTIMES_ENABLE_EXCEPTIONS)
   serialize_lit_param(SERIALIZED_LIT_PARAMS enable_exceptions False)
 endif()
 
-if (NOT LIBCXX_ENABLE_RTTI)
+if (NOT RUNTIMES_ENABLE_RTTI)
   serialize_lit_param(SERIALIZED_LIT_PARAMS enable_rtti False)
 endif()
 

libcxx/utils/ci/run-buildbot

@@ -617,8 +617,7 @@ aarch64)
 aarch64-no-exceptions)
     clean
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/AArch64.cmake" \
-                   -DLIBCXX_ENABLE_EXCEPTIONS=OFF \
-                   -DLIBCXXABI_ENABLE_EXCEPTIONS=OFF
+                   -DRUNTIMES_ENABLE_EXCEPTIONS=OFF
     check-runtimes
 ;;
 # Aka Armv8 32 bit
@@ -650,10 +649,9 @@ armv7m-picolibc)
 armv7m-picolibc-no-exceptions)
     test-armv7m-picolibc \
         -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Armv7M-picolibc.cmake" \
-        -DLIBCXXABI_ENABLE_EXCEPTIONS=OFF \
-        -DLIBCXXABI_ENABLE_STATIC_UNWINDER=OFF \
-        -DLIBCXX_ENABLE_EXCEPTIONS=OFF \
-        -DLIBCXX_ENABLE_RTTI=OFF
+        -DRUNTIMES_ENABLE_EXCEPTIONS=OFF \
+        -DRUNTIMES_ENABLE_RTTI=OFF \
+        -DLIBCXXABI_ENABLE_STATIC_UNWINDER=OFF
 ;;
 clang-cl-dll)
     clean

libcxxabi/CMakeLists.txt

@@ -46,9 +46,6 @@ include(CMakeDependentOption)
 include(HandleCompilerRT)
 
 # Define options.
-option(LIBCXXABI_ENABLE_EXCEPTIONS
-  "Provide support for exceptions in the runtime.
-  When disabled, libc++abi does not support stack unwinding and other exceptions-related features." ON)
 option(LIBCXXABI_ENABLE_ASSERTIONS "Enable assertions independent of build mode." ON)
 option(LIBCXXABI_ENABLE_PEDANTIC "Compile with pedantic enabled." OFF)
 option(LIBCXXABI_ENABLE_WERROR "Fail and stop if a warning is triggered." OFF)
@@ -325,19 +322,6 @@ add_definitions(-D_LIBCPP_BUILDING_LIBRARY)
 # Get feature flags.
 add_compile_flags_if_supported(-fstrict-aliasing)
 
-# Exceptions
-if (LIBCXXABI_ENABLE_EXCEPTIONS)
-  # Catches C++ exceptions only and tells the compiler to assume that extern C
-  # functions never throw a C++ exception.
-  add_compile_flags_if_supported(-EHsc)
-  # Do we really need to be run through the C compiler ?
-  add_c_compile_flags_if_supported(-funwind-tables)
-else()
-  add_compile_flags_if_supported(-fno-exceptions)
-  add_compile_flags_if_supported(-EHs-)
-  add_compile_flags_if_supported(-EHa-)
-endif()
-
 # Assert
 string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)
 if (LIBCXXABI_ENABLE_ASSERTIONS)

libcxxabi/src/CMakeLists.txt

@@ -25,7 +25,7 @@ if (LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS)
   )
 endif()
 
-if (LIBCXXABI_ENABLE_EXCEPTIONS)
+if (RUNTIMES_ENABLE_EXCEPTIONS)
   list(APPEND LIBCXXABI_SOURCES
     cxa_exception.cpp
     cxa_personality.cpp
@@ -258,7 +258,7 @@ endif()
 # whether the exception runtime machinery is provided.
 reexport_symbols("${CMAKE_CURRENT_SOURCE_DIR}/../lib/std-exceptions.exp")
 
-if (LIBCXXABI_ENABLE_EXCEPTIONS)
+if (RUNTIMES_ENABLE_EXCEPTIONS)
   reexport_symbols("${CMAKE_CURRENT_SOURCE_DIR}/../lib/itanium-exceptions.exp")
 
   if ("${CMAKE_OSX_ARCHITECTURES}" MATCHES "^(armv6|armv7|armv7s)$")

libcxxabi/test/CMakeLists.txt

@@ -66,7 +66,7 @@ set(SERIALIZED_LIT_PARAMS "# Lit parameters serialized here for llvm-lit to pick
 
 serialize_lit_string_param(SERIALIZED_LIT_PARAMS compiler "${CMAKE_CXX_COMPILER}")
 
-if (NOT LIBCXXABI_ENABLE_EXCEPTIONS)
+if (NOT RUNTIMES_ENABLE_EXCEPTIONS)
   serialize_lit_param(SERIALIZED_LIT_PARAMS enable_exceptions False)
 endif()
 

runtimes/CMakeLists.txt

@@ -33,6 +33,9 @@ list(INSERT CMAKE_MODULE_PATH 0
   "${CMAKE_CURRENT_SOURCE_DIR}/../llvm/cmake/modules"
 )
 
+# Include options to configure the runtime projects
+include(cmake/Modules/LanguageFlags.cmake)
+
 # We order libraries to mirror roughly how they are layered, except that compiler-rt can depend
 # on libc++, so we put it after.
 set(LLVM_DEFAULT_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;libclc;openmp;offload")

runtimes/cmake/Modules/HandleFlags.cmake

@@ -1,3 +1,9 @@
+#
+# This file defines legacy functions to detect and set compiler flags
+# used throughout the runtimes. Please move away from using these
+# functions in favour of using interface targets (see for example
+# LanguageFlags.cmake).
+#
 
 include(CheckCXXCompilerFlag)